code: def testStringMatrixAggregation(self):
      p = Pool(
          {
              "foo": [
                  ["qt", "is", "sweet"],
                  ["peanut", "butter", "jelly time"],
                  ["yo no", "hablo", "espanol"],
              ]
          }
      )
  
      results = PoolAggregator()(p)
  
      self.assertEqualVector(results.descriptorNames(), ["foo"])
      self.assertEqualMatrix(
          results["foo"],
          [
              ["qt", "is", "sweet"],
              ["peanut", "butter", "jelly time"],
              ["yo no", "hablo", "espanol"],
          ],
      )
  
file_path: essentia/test/src/unittests/stats/test_poolaggregator.py
imports: from essentia_test import *
label_desc: Use image node_id 5 for calling the TestPoolAggregator obj's underlying member method code with example usage: obj.testStringMatrixAggregation() without return types